1. Field of the Invention
This invention relates to a recording or reproducing apparatus, and more particularly to a stabilizing member which is arranged to stabilize the abutting state of a head on a recording medium.
2. Description of the Related Art
Recording or reproducing apparatuses of the kind arranged to perform recording or reproduction on or from a sheet-shaped recording medium such as a flexible magnetic disc or the like have been known.
The apparatus of this kind uses a head supporting device (hereinafter referred to as a pad) which is arranged to generate fluidic pressure through the travel of the magnetic sheet to push the magnetic sheet against the head for stable contact of the magnetic sheet with the magnetic head while the sheet is traveling.
Generally, the pad is arranged to be in a shape as shown in FIGS. 1(a) and 1(b) of the accompanying drawings. Referring to these figures, the pad 100 is disposed around the magnetic head 4. A flat part 104 of the pad 100 has a slot 108 arranged in its middle part on one side of the pad 100 facing the magnetic sheet 3 (see FIG. 2) to allow the magnetic head 4 to pass therethrough. Projecting strip parts 101 and 103 are formed in concentric circular shapes to protrude to a given height from the flat part 104 and are spaced at a given distance through an annular groove part 102 around the periphery of the flat part 104. The projecting strip parts 101 and 103 are provided with cutout parts 105 and 106. These cutout parts 105 and 106 are arranged on a downstream side D of the movement of the magnetic sheet 3, in the direction of arrow A, to eject an air stream generated by the rotation of the magnetic sheet 3 in such a way as to control negative pressure brought forth by the pad 100.
The sheet sliding-contact faces 101a and 103a of the projecting strip parts 101 and 103 of the pad 100 are in a flat shape. With the pad 100 disposed around the magnetic head 4 in the above-stated manner, when the magnetic sheet 3 is caused to rotate, a stream of air takes place between the pad 100 and the magnetic sheet 3 to bring forth a negative pressure which sucks the magnetic sheet 3. FIG. 8(b) shows the results of fluidic analysis of the distribution of pressure between the pad 100 and the magnetic sheet 3. In the case of FIG. 8(b), the distribution of pressure is taken along a line B--B shown in FIG. 1(a). The points P1 to P8 of FIG. 8(b) correspond to points P1 to P8 of FIG. 1(a). Further, the planar distribution of a contact force between the pad 100 and the magnetic sheet 3 is as shown in FIG. 4(b).
In the case of the conventional device described above, the upper faces 101a and 103a of the projecting strip parts 101 and 103 are formed approximately on the same plane. Therefore, when the magnetic sheet 3 is sucked by the pad 100 into contact with the head 4, the distribution of the contact force which is as shown in FIG. 4(b) causes the magnetic sheet 3 to come into contact with the sliding-contact faces 101a and 103a of the pad 100 in a greatly partial manner. The partial contact then tends to damage the magnetic sheet 3 or to cause fluctuations in the negative pressure on a spindle motor, uneven rotation, jitters and so on.
Further, macroscopically considered, the force of sucking is weak on the downstream side D of the head 4 in the rotating direction of the magnetic sheet 3 to cause the deformation of the magnetic sheet 3 to become asymmetric relative to the head 4 as shown in FIG. 5(b). Under such a condition, the head 4 comes into strong contact with the magnetic sheet 3 on its upstream side U to result in a partial abrasion of the head 4.
The conventional device has presented another problem: since the magnetic sheet 3 is sucked by the negative pressure which is brought forth by the groove part 102, the magnetic sheet 3 is deformed, considering it microscopically, at the projecting strip parts 101 and 103 as shown in FIG. 9(b). The magnetic sheet 3 thus comes into contact with the edges 101b and 103b of the projecting strip parts 101 and 103. This condition not only tends to cause the magnetic sheet 3 to be damaged by the pad 100 but also might hinder recording or reproduction.